In many situations, finding an asset within a facility can be a cumbersome and time-consuming exercise. Worker productivity is reduced by requiring the worker to search for the asset. Further, the benefits of a certain piece of equipment or asset are reduced by having it under-utilized, thereby in many situations necessitating the purchase of more assets in order to offset this down-time.
In order to overcome the above inefficiencies, in some situations, facilities have installed asset tracking systems. An asset tracking system, as used herein, is defined as a real-time or near real-time system in which an asset location is continually updated. Such systems generally include means for locating an object in a facility through the attachment of an indicia to the object. Indicia include radio frequency tags. Such a system records the location of the object and the radio frequency tag is used to identify the location of the object. Receivers in each location typically convey identifiers from a tag to a centralized computer.
The problem with asset tracking is the cost of implementing the infrastructure required for this tracking. Each location needs to include a receiver for receiving signals from assets and this receiver needs to continually communicate with a centralized database in order to constantly know the location of assets.
Asset tracking is useful, for example, in warehouse situations where a large number of assets exist in a small area. The cost of implementing a number of receivers in this small area is sufficiently low that asset tracking is worthwhile. Situations with sufficiently high-valued assets can also justify the required infrastructure costs of an installed tracking system.
Asset tracking, however, is not worthwhile in situations where there are a relatively small number of assets in a large location. Such a location can include, for example, a hospital setting in which the location of pieces of equipment sometime need to be determined. In such a situation, the cost of implementing an asset tracking system can be prohibitive due to the infrastructure requirements of this system. Other illustrative examples are a) materials and/or equipment tracking in manufacturing facilities and b) goods tracking in a distribution centre.
An asset “location” system is a better solution for such an environment. An asset “location” system is a system in which an asset is periodically located and this information is stored on a database. One such system includes U.S. Pat. No. 6,600,418 to Francis et al. Francis teaches the use of a radio frequency identification tag (RFID) on both objects and in locations. A palette truck moving the objects includes an interrogator and a receiver which records both the location of the object and the object identification. Using the RFID tags on both location and the object, a database on the palette truck can store the location of an asset.
One problem with Francis is the use of an RFID tag for both the location and the object identification. RFID will identify an area of poorly controlled and poorly defined size and dimensions for the location of an object. Further, since both the object and the location uses RFID tags, it is possible that the palette truck in Francis will receive an identifier for the location from one tag which does not necessarily identify the correct location for the object identified by a second tag.
A second problem of Francis is that it requires interrogation, thus making the tags and markers more complicated and costly. Francis further does not disclose the period collection of data for the movement of assets since Francis assumes that these assets will be moved with a fork-lift truck and, therefore, the new asset location will be registered in the database.
Another tracking system includes U.S. Pat. No. 6,154,139 to Heller. Heller teaches the use of RF and IR to locate subjects. The system has asset tags which transmit both IR and RF to a dual technology receiver. This implementation limits the receiver to be within line of sight for the IR communication to function and provide location information. This, as a result, requires additional receivers to be installed to get IR location information and limits the function of the non-line of site receivers to only RF information. This system is not suitable for portable receivers due to the lack of location specific IR information since it is also an IR receiver. Therefore, it does not address the high infrastructure costs of fixed receivers in an asset tracking system.
Another tracking system includes U.S. Pat. No. 6,542,114 to Eagleson et al. Eagleson teaches the the use of LF transmit signposting, an asset tag with an LF receiver and RF transmitter, along with an RF receiver which is fixed into the facility infrastructure. Eagleson does not teach the use of a portable RF receiver and therefore also does not address the high infrastructure costs required to install a fully fixed network of receivers.
In situations such as in hospitals, schools, laboratories or other facilities in which objects can be moved by people, it is desirable, therefore, to have a low-cost system which can periodically be updated to indicate the location of assets and to do so accurately.